The present invention relates to a full-color hologram and a method of producing the same. More particularly, the present invention relates to a full-color hologram capable of generating a bright image and reproducing colors in all color regions with favorable reproducibility and also relates to a method of producing the full-color hologram.
Conventionally, a hologram original plate for color holograms and a duplicate thereof are made by multiple recording or multilayer recording using three laser light having three wavelengths in the three primary color regions of blue, green and red, i.e. 400 nm to 500 nm (blue), 500 nm to 600 nm (green), and 600 nm to 700 nm (red).
Meanwhile, a proposition is made in Applied Optics Vol. 12, No. 3, pp. 496-499 to form a multicolor hologram from holograms recorded separately by using laser light of four wavelengths, i.e. 476.2 nm, 520.8 nm, 568.2 nm and 632.8 nm.
When a color hologram recorded with the above-described three wavelengths is illuminated with a white light source to reconstruct a holographic image, colors cannot satisfactorily be reproduced. Therefore, the reconstructed image is inferior in color tone reproduction and unfavorably dark.
Methods for producing holograms capable of generating bright images include one that uses a wavelength (550 nm to 560 nm) in the vicinity of the peak wavelength 555 nm of a spectral luminous efficiency curve as a reconstruction wavelength for green. However, when a wavelength in the range of 550 nm to 560 nm is recorded as a reconstruction wavelength in the green region, if the reconstruction wavelength for blue is 458 nm, as shown in FIG. 11, blue green in the chromaticity diagram cannot be reproduced. If 488 nm is used as a reconstruction wavelength for blue, the full shade of blue cannot be reproduced. It is very difficult with the recording using three wavelengths to realize satisfactory color reproduction such as to express colors in all color regions divided into 23 sections on the chromaticity diagram (in the chromaticity diagram, it is possible to reproduce only colors within a triangle formed by connecting three wavelengths with straight lines. In FIG. 11, 630 nm is used as a reconstruction wavelength for red. It should be noted that the chromaticity diagram is quoted from xe2x80x9cJIS Handbook Colorxe2x80x9d).
On the other hand, the above-described proposition to record a multicolor hologram by using four wavelengths considers mainly white color reproduction and makes no proposition concerning how to select recording wavelengths to construct a full-color hologram capable of generating a bright image and reproducing colors in all color regions.
The present invention was made in view of the above-described problems with the prior art. An object of the present invention is to provide a full-color hologram recorded with four wavelengths, which is capable of generating a bright image and reproducing colors in all color regions, and also provide a method of producing the full-color hologram.
To attain the above-described object, the present invention provides a full-color hologram formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively.
In addition, the present invention provides a method of producing a full-color hologram. The full-color hologram is formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. In the full-color hologram producing method, as one recording wavelength in the green region, 514.5 nm from an argon laser or 532 nm from an LD pumped laser is used, and as another recording wavelength in the green region, a wavelength not shorter than 555 nm is used.
In this case, it is desirable that as the another recording wavelength in the green region, a wavelength in the range of 565 nm to 590 nm should be used, and that the reconstruction wavelengths should be shifted 15 nm to 40 nm to the shorter wavelength side by shrinkage of a photosensitive material after recording or by wavelength shift effected by a pressure-sensitive adhesive.
As the another recording wavelength in the green region, a wavelength in the range of 565 nm to 600 nm from a dye laser may be used.
In addition, the present invention provides another method of producing a full-color hologram. The full-color hologram is formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. The full-color hologram is made by holographic duplication from a hologram original plate. In the full-color hologram producing method, the hologram original plate is formed from a stack of four layers of photosensitive material, each layer containing a hologram recorded for each corresponding wavelength.
In addition, the present invention provides a further method of producing a full-color hologram. The full-color hologram is formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. The full-color hologram is made by holographic duplication from a hologram original plate. In the full-color hologram producing method, the hologram original plate is formed as follows. A wavelength in the red region and one wavelength in the green region are recorded in the same layer of photosensitive material. A wavelength in the blue region and another wavelength in the green region are recorded in the same layer of photosensitive material that is different from the first-mentioned layer. The two layers are stacked on top of each other to form a hologram original plate.
In addition, the present invention provides a still further method of producing a full-color hologram. The full-color hologram is formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. The full-color hologram is made by holographic duplication from a hologram original plate. In the full-color hologram producing method, the hologram original plate is formed as follows. A wavelength in the red region is recorded in a layer of photosensitive material. Two wavelengths in the green region are recorded in the same layer of photosensitive material that is different from the layer in which the wavelength in the red region has been recorded. A wavelength in the blue region is recorded in a layer of photosensitive material that is different from the former two layers. The three layers are stacked on top of each other to form a hologram original plate.
In addition, the present invention provides a still further method of producing a full-color hologram. The full-color hologram is formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. The full-color hologram is made by holographic duplication from a hologram original plate. In the full-color hologram producing method, the hologram original plate is formed as follows. A wavelength in the red region is recorded in a layer of photosensitive material. One wavelength in the green region is recorded in a layer of photosensitive material that is different from the layer in which the wavelength in the red region has been recorded. Another wavelength in the green region and a wavelength in the blue region are recorded in the same layer of photosensitive material that is different from the former two layers. The three layers are stacked on top of each other to form a hologram original plate.
In addition, the present invention provides a still further method of producing a full-color hologram. The full-color hologram is formed by multiple recording or multilayer recording with four different dominant wavelengths for reconstruction. The full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. The full-color hologram is made by holographic duplication from a hologram original plate. In the full-color hologram producing method, the hologram original plate is formed by recording four wavelengths in the same layer of photosensitive material.
In the present invention, the full-color hologram has one reconstruction wavelength in the vicinity of the peak wavelength 555 nm of the spectral luminous efficiency curve, i.e. in the range of 550 nm to 560 nm, and further has three other reconstruction wavelengths in the three primary color regions of red, blue and green, i.e. in the three regions of 615 nm to 680 nm, 380 nm to 470 nm, and 485 nm to 515 nm, respectively. Therefore, it is possible to obtain a full-color hologram capable of generating a bright image and reproducing colors in all color regions with favorable reproducibility.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.